Traditionally, metal strip stock such as steel or aluminum in rolling mills is cleaned by systems which vary in complexity, cost and effectiveness. In many installations, motor driven cleaning brushes are mounted above and below the moving strip stock and sprays of water, or water containing additives, are directed onto the strip while the power brushes do their work. Such prior art systems also involve liquid pumps and heaters and tend to be very costly to operate and maintain and also consume large amounts of energy and water. Cleaning systems employing brushes have also proven to be relatively inefficient for cleaning strips which travel at comparatively high speeds common in modern mills.
The present invention has been developed to overcome the above drawbacks of the known prior art while providing an even more efficient and thorough cleaning of the product with greater economy, less requirement for expensive maintenance, and a substantial savings of energy.
The method embodying the invention eliminates entirely the necessity for motor operated brushes and attendant heavy and costly equipment. In essence, the invention comprises an intermixing of ambient water and steam at the entrance of a venturi chamber where the steam condenses and elevates the temperature of the water. The water accelerates through the throat of the venturi chamber and on exiting this throat expands into a venturi exit chamber of enlarged cross section where the pressure of the heated water is increased substantially above incoming steam pressure. The water having elevated pressure and temperature is delivered through piping to two or more spray cleaning headers on opposite sides of the moving strip where multiple opposing sprays are directed onto opposite sides of the strip. The optional cleaning additive can be drawn by vacuum into the entrance chamber of the venturi whenever needed by the mere operation of a metering valve. The invention can operate in a manual mode or an automatic mode depending upon the requirements of particular installations and the degree of convenience and sophistication desired.
Other aspects of the invention will become apparent during the course of the following detailed description.
The below-listed prior U.S. Pat. Nos. are noted herein under 37 C.F.R. 1.56:
2,319,591 PA1 2,391,422 PA1 2,508,766 PA1 2,592,884 PA1 2,861,838 PA1 2,943,797 PA1 3,380,658 PA1 3,438,583 PA1 3,473,481 PA1 3,510,065 PA1 3,810,787 PA1 3,873,024 PA1 4,029,260.